1. Abstract Patients with a first episode of psychosis (FEP) often have substantial amounts of morbidity during the months and years after onset, and elevated mortality in later years. Growing amounts of evidence suggest that early treatment might help; several recent national and state policies have increased focus, shifted priorities, and provided additional resources to enhance FEP care, yet important gaps remain in the clinical knowledge base. This project helps build the data foundation for addressing these gaps, and leverages the recently launched Massachusetts Department of Mental Health (DMH) Center of Excellence in Early Psychosis (CoE). This state- led effort is mandating standardized data collection on the delivery structure, processes, and outcomes of FEP care, funding the data collection, and creating a process for improving data collection over time. Funding for this work comes from recent SAMHSA policy directives concerning the state Mental Health Block Grants. In close collaboration with DMH, this project will address three aims: 1) Synthesize the longitudinal data collected by the state, including reviewing the data quality and altering the state data collection processes if needed; 2) Validate care delivery measures that form the basis of clinical feedback and research; and 3) Integrate multiple dimensions and perspectives of care outcomes. The structural data include information on clinic staffing and CSC fidelity; the clinical data include measures on symptomatic stability, cognitive function, safety-related outcomes, symptomatic relapse, and community function; the claims data come from the APCD used in Project 1. Working with the Methods Core, Project 2 will pay special attention to inherent challenges in data collection in FEP research such as complexity of phenotypes and patterns of missingness (i.e. random vs. systematic). Project 3 will result in validated, longitudinal data on patient phenotypes, which we will use in Project 3 to examine clinical heterogeneity, and in pilot studies described in the Administrative Core. The protocols and measures developed will inform state and state efforts to enhance data collection in FEP research. In sum, this project takes creates the foundation through which large amounts of raw data collected by the state become the basis of research that converts these data into useful clinical and policy knowledge.